The present invention relates to forms of administration of tramadol, retarded by a coating, which contain the active substance tramadol as tramadol saccharinate, optionally together with other auxiliary substances.
The very readily water-soluble tramadol hydrochloridexe2x80x94(1RS,2RS)-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol hydrochloridexe2x80x94is often used for the control of intense and moderately intense pain.
The administration of tramadol hydrochloride in the form of sustained-release preparations represents a therapeutic improvement for this active substance. Even for this active substance with its relatively short half-life in the organism, retardation makes it possible to provide a preparation with a long-lasting action and also, through more constant blood levels, to reduce side effects and improve the patients"" observance of the dosage instructions.
The active substance tramadol hydrochloride can be retarded e.g. by the application of sustained-release film coatings to pharmaceutical forms containing tramadol hydrochloride. However, retardation of this active substance with the aid of film coatings is relatively expensive because film coatings from aqueous coating systems for very readily water-soluble active substances of this kind frequently constitute an inadequate diffusion barrier and the permeability of these film coatings for tramadol hydrochloride usually changes during storage (P. B. O""Donnell, J. W. McGinity, xe2x80x9cMechanical Properties of Polymeric Films, Prepared from Aqueous Polymeric Dispersions in Aqueous Polymeric Coatings for Pharmaceutical Dosage Formsxe2x80x9d, Drugs and the Pharmaceutical Science, vol. 79, ed. J. W. McGinity, Marcel Decker, New York, Basle, Hong Kong 1997).
The manufacture of these retarded tramadol hydrochloride preparations therefore requires relatively expensive coating processes with multilayer films or time-consuming tempering processes, as described in U.S. Pat. Nos. 5,645,858, 5,580,578, 5,681,585 or U.S. Pat. No. 5,472,712, in K. Bauer, xe2x80x9cCoated Pharmaceutical Dosage Formsxe2x80x9d, Medpharm Scientific Publishers, Stuttgart 1998, B. Sutter, Thesis, University of Dxc3xcsseldorf, 1987, or in F. N. Christensen, Proceed. Intern. Symp. Contr. Rel. Bioact. Mater. 17, 124, 1990. If such coatings are applied from organic solvents, the associated environmental and solvent residue problems further increase the gcost of retarding tramadol hydrochloride.
The object of the invention was therefore to provide a form of administration, or a pharmaceutical formulation, of the active substance tramadol, retarded with the aid of a coating, whose active substance release profile immediately after preparation is stable on storage without the need for laborious and expensive coating processes or time-consuming and hence cost-intensive tempering processes.
According to the invention, this object is achieved by the preparation of forms of administration, provided with a sustained-release coating, which contain the active substance tramadol as tramadol saccharinate, optionally together with other pharmaceutically acceptable auxiliary substances or excipients.
Surprisingly, the active substance release profile of the retarded forms of administration according to the invention immediately after preparation is stable on storage without the sustained-release coating having to undergo tempering after the conventional drying.
To prepare the tramadol saccharinate, tramadolxe2x80x94(1RS,2RS)-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanolxe2x80x94and/or at least one appropriate, preferably water-soluble salt are reacted with saccharin and/or at least one, preferably water-soluble saccharin salt. The tramadol salt used is preferably tramadol hydrochloride and the saccharin salt used is preferably the sodium, potassium, calcium or ammonium salt and particularly preferably the sodium salt.
The tramadol saccharinate can also be formed in situ during the preparation of the forms of administration.
In terms of the present invention, in situ formation means that a readily water-soluble salt of tramadol is mixed with a water-soluble salt of saccharin, moistened and granulated several times, optionally extruded and/or formulated under some other energy input, preferably under pressure and/or with the application of heat.
For the in situ formation of tramadol saccharinate, the tramadol can be used as a water-soluble, pharmaceutically acceptable salt, preferably as tramadol hydrochloride, and the water-soluble, pharmaceutically acceptable salt of saccharin used is preferably the sodium, potassium, calcium or ammonium salt and particularly preferably the sodium salt.
The forms of administration according to the invention, provided with a sustained-release coating film, are preferentially suitable for oral administration.
In one preferred embodiment of the present invention, the forms of administration according to the invention are tablets, capsules or suspensions.
In another preferred embodiment of the present invention, the forms of administration according to the invention are multiparticulate, preferably in the form of microtablets, microcapsules, micropellets, granules, active substance crystals or pellets, optionally filled into capsules or compressed to tablets, or in a hydrophilic or lipophilic liquid, preferably as a homogeneous suspension, and particularly preferably in the form of juices or oral dispersions. If the forms of administration according to the invention are granules or pellets, they can preferably have a size in the range 0.1 to 3 mm and particularly preferably in the range 0.5 to 2 mm.
If the forms of administration according to the invention are microtablets, they can preferably have a diameter in the range 0.5 to 5 mm, particularly preferably in the range 1 to 3 mm and very particularly preferably in the range 1 to 2 mm.
If the forms of administration according to the invention are active substance crystals, microparticles, micropellets or microcapsules, they can preferably have a diameter in the range 10 xcexcm to 1 mm, particularly preferably in the range 15 xcexcm to 0.5 mm and very particularly preferably in the range 30 xcexcm to 200 xcexcm.
Depending on the embodiment, the forms of administration according to the invention can also contain, as additional constituents, the conventional auxiliary substances known to those skilled in the art.
If the forms of administration according to the invention are tablets or microtablets, they can preferably contain, as additional auxiliary substances, microcrystalline cellulose, cellulose ethers, lactose, starch and starch derivatives, sugar alcohols, calcium hydrogenphosphate and the conventional binders, flow regulators, lubricants and optionally disintegrants known to those skilled in the art.
If the forms of administration according to the invention are pellets, granules or micropellets, they can preferably contain, as additional auxiliary substances, microcrystalline cellulose, cellulose ethers, lactose, starch and starch derivatives, sugar alcohols, calcium hydrogenphosphate, fatty alcohols, glycerol esters or fatty acid esters.
If the forms of administration according to the invention are microcapsules or microparticles, they can contain the conventional auxiliary substances known to those skilled in the art, depending on the type of production process.
The various forms of administration according to the invention can be produced by different methods known to those skilled in the art.
If the form of administration according to the invention is tablets, they can be produced for example by the compression of granules produced by means of moist, dry or hot-melt granulation, or by direct tableting of the tramadol saccharinate, optionally with additional auxiliary substances. The tablets can also be produced by the compression of coated pellets, active substance crystals, microparticles or microcapsules.
The pellet form of administration according to the invention can be produced by extrusion and spheronization, by cumulative pelleting or by direct pelleting in a high-speed mixer or in a rotary fluidized bed. It is particularly preferred to produce the pellets by the extrusion of moist masses and subsequent spheronization.
Microcapsules are produced by conventional microencapsulation processes, e.g. by spray drying, spray congelation or coacervation.
In one preferred embodiment of the forms of administration according to the invention, the sustained-release coating film is preferably based on a water-insoluble, optionally modified, natural and/or synthetic polymer, on a natural, semisynthetic or synthetic wax, on a fat or fatty alcohol, or on a mixture of at least two of the above-mentioned components.
The water-insoluble polymers used to produce a sustained-release coating are preferably poly(meth)acrylates, particularly preferably poly(C1-4)alkyl (meth)acrylates, poly(C1-4)dialkylamino(C1-4)alkyl (meth)acrylates and/or copolymers thereof, and very particularly preferably copolymers of ethyl acrylate and methyl methacrylate with a monomer molar ratio of 2:1 (Eudragit NE30D(copyright)), copolymers of ethyl acrylate, methyl methacrylate and trimethylammonium ethyl methacrylate-chloride with a monomer molar ratio of 1:2:0.1 (Eudragit RS(copyright)), copolymers of ethyl acrylate, methyl methacrylate and trimethylammonium ethyl methacrylate-chloride with a monomer molar ratio of 1:2:0.2 (Eudragit RL(copyright)), or a mixture of at least two of the above-mentioned copolymers. These coating materials are commercially available as 30 wt. % aqueous latex dispersions, i.e. as Eudragit RS30D(copyright), Eudragit NE30D(copyright) or Eudragit RL30D(copyright), and are preferably also used as such for coating purposes.
Other preferred water-insoluble polymers which can be used to produce the sustained-release coating of the forms of administration according to the invention are polyvinyl acetates, optionally in combination with additional auxiliary substances. They are commercially available as an aqueous dispersion containing 27 wt. % of polyvinyl acetate, 2.5 wt. % of povidone and 0.3 wt. % of sodium laurylsulfate (Kollicoat SR 30 D(copyright)).
In another preferred embodiment, the sustained-release coatings of the forms of administration according to the invention are based on water-insoluble cellulose derivatives, preferably alkyl celluloses, e.g. ethyl cellulose, or cellulose esters, e.g. cellulose acetate. The ethyl cellulose or cellulose acetate coatings are preferably applied from aqueous pseudolatex dispersion. Aqueous ethyl cellulose pseudolatex dispersions are commercially available as 30 wt. % dispersions (Aquacoat(copyright)) or as 25 wt. % dispersions (Surelease(copyright)).
As natural, semisynthetic or synthetic waxes, fats or fatty alcohols, the sustained-release coating of the forms of administration according to the invention can preferably be based on carnauba wax, beeswax, glycerol monostearate, glycerol monobehenate (Compritol ATO888(copyright)), glycerol ditripalmitostearate (Precirol ATO5(copyright)), microcrystalline wax, cetyl alcohol, cetylstearyl alcohol or a mixture of at least two of these components.
If the sustained-release coating is based on a water-insoluble, optionally modified, natural and/or synthetic polymer, the coating dispersion or solution can contain, in addition to the appropriate polymer, a conventional, physiologically acceptable plasticizer known to those skilled in the art, in order to lower the required minimum film temperature.
Examples of suitable plasticizers are lipophilic diesters of a C6-C40 aliphatic or aromatic dicarboxylic acid and a C1-C8 aliphatic alcohol, e.g. dibutyl phthalate, diethyl phthalate, dibutyl sebacate or diethyl sebacate, hydrophilic or lipophilic citric acid esters, e.g. triethyl citrate, tributyl citrate, acetyltributyl citrate or acetyltriethyl citrate, polyethylene glycols, propylene glycol, glycerol esters, e.g. triacetin, Myvacet(copyright) (acetylated mono- and diglycerides, C23H44O5 to C25H47O7), medium-chain triglycerides Miglyol(copyright)), oleic acid or mixtures of at least two of said plasticizers.
Aqueous dispersions of Eudragit RS(copyright) and optionally Eudragit RL(copyright) preferably contain triethyl citrate.
The sustained-release coating of the form of administration according to the invention preferably contains the plasticizer(s) in amounts of 5 to 50 wt. %, particularly preferably 10 to 40 wt. % and very particularly preferably 10 to 30 wt. %, based on the amount of polymer(s) used. In individual cases, for example for cellulose acetate, it is also possible to use larger amounts of plasticizers, preferably of up to 110 wt. %.
The sustained-release coating can also contain other conventional auxiliary substances known to those skilled in the art, e.g. lubricants, preferably talcum or glycerol monostearate, coloured pigments, preferably iron oxides or titanium dioxide, or surfactants, e.g. Tween 80(copyright).
The tramadol release profile obtained immediately after production of the form of administration according to the invention can be adjusted by the conventional methods known to those skilled in the art, e.g. by means of the thickness of the coating or by the use of additional auxiliary substances as constituents of the coating. Examples of suitable auxiliary substances are hydrophilic or pH-dependent pore-forming agents such as sodium carboxymethyl cellulose, cellulose acetate-phthalate, hydroxypropyl methyl cellulose acetate-succinate, lactose, polyethylene glycol or mannitol, or water-soluble polymers such as polyvinylpyrrolidone or water-soluble celluloses, preferably hydroxypropyl methyl cellulose or hydroxypropyl cellulose.
To further enhance the retardation, the sustained-release coating can also contain insoluble or lipophilic auxiliary substances such as alkylated silicon dioxide, which is marketed e.g. as Aerosil R972(copyright), or magnesium stearate.
The forms of administration according to the invention for the release of tramadol saccharinate can additionally have an enteric coating which dissolves as a function of pH. Because of this coating, the forms of administration according to the invention can pass through the stomach undissolved and the tramadol saccharinate is only released in the intestinal tract. The enteric coating preferably dissolves at a pH of between 5 and 7.5.
The enteric coating is preferably based on methacrylic acid/methyl methacrylate copolymers with a monomer molar ratio of 1:1 (Eudragit L(copyright)), methacrylic acid/methyl methacrylate copolymers with a monomer molar ratio of 1:2 (Eudragit S(copyright)), methacrylic acid/ethyl acrylate copolymers with a monomer molar ratio of 1:1 (Eudragit L30D-55(copyright)), methacrylic acid/methyl acrylate/methyl methacrylate copolymers with a monomer molar ratio of 7:3:1 (Eudragit FS(copyright)), shellac, hydroxypropyl methyl cellulose acetate-succinates, cellulose acetate-phthalates or a mixture of at least two of these components, which can optionally also be used in combination with the above-mentioned water-insoluble poly(meth)acrylates, preferably in combination with Eudragit NE30D(copyright) and/or Eudragit RL(copyright) and/or Eudragit RS(copyright).
The coatings of the form of administration according to the invention can be applied by the conventional processes known to those skilled in the art which are suitable for the particular coating, e.g. by the spraying of solutions, dispersions or suspensions, by the hot-melt process or by the powder application process. The solutions, dispersions or suspensions can be used in the form of aqueous or organic solutions or dispersions, preferably aqueous dispersions. Organic solvents which can be used are alcohols, for example ethanol or isopropanol, ketones, e.g. acetone, esters, for example ethyl acetate, and chlorinated hydrocarbons, e.g. dichloromethane, preference being given to alcohols and ketones. It is also possible to use mixtures of at least two of the above-mentioned solvents.
These processes are known from the state of the art, e.g. H. Sucker, Georg Thieme Verlag, 1991, pages 347 et seq. They are introduced here by way of reference and thus form part of the disclosure.
If the forms of administration according to the invention are multiparticulate, the sustained-release coating is preferably applied in such a way that, after preparation, the multiparticulate forms containing the tramadol saccharinate are coated with the appropriate polymers and optionally other auxiliary substances from aqueous and/or organic media, preferably from aqueous media, by the fluidized bed process, and the coating is preferably dried simultaneously at conventional temperatures in the fluidized bed without subsequently being tempered. In the case of poly(meth)acrylate coatings, the coating is preferably dried at an air inlet temperature in the range 30 to 50xc2x0 C. and particularly preferably in the range 35 to 45xc2x0 C.
In the case of coatings based on cellulose, e.g. ethyl cellulose or cellulose acetate, drying preferably takes place at a temperature in the range 50 to 80xc2x0 C. and particularly preferably in the range 55 to 65xc2x0 C.
Wax coatings can be applied by hot-melt coating in a fluidized bed and, after coating, cooled to complete the solidification at temperatures below the appropriate melting range. Wax coatings can also be applied by spraying solutions thereof in organic solvents.
For further modification of the active substance release profile, the sustained-release forms of administration according to the invention can also contain tramadol saccharinate in a sustained-release matrix, preferably as a uniform distribution.
Matrix materials which can be used are physiologically compatible, hydrophilic materials known to those skilled in the art. The hydrophilic matrix materials used are preferably polymers and particularly preferably cellulose ethers, cellulose esters and/or acrylic resins. The matrix materials used are very particularly preferably ethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose, poly(meth)acrylic acid and/or derivatives thereof such as their salts, amides or esters.
Other preferred matrix materials are those consisting of hydrophobic materials such as hydrophobic polymers, waxes, fats, long-chain fatty acids, fatty alcohols or corresponding esters or ethers, or mixtures thereof. The hydrophobic materials used are particularly preferably C12-C30 fatty acid mono- or diglycerides and/or C12-C30 fatty alcohols and/or waxes, or mixtures thereof.
It is also possible to use mixtures of the above-mentioned hydrophilic and hydrophobic materials as the sustained-release matrix material.
The sustained-release matrix can be prepared by the conventional methods known to those skilled in the art.
In another preferred embodiment, the forms of administration according to the invention contain the active substance tramadol not only in its retarded form but also in its non-retarded form, e.g. as tramadol hydrochloride. By combination with the immediately released active substance, a high initial dose can be achieved for the rapid alleviation of pain. The slow release from the retarded form then prevents the analgesic effect from diminishing.
The amount of tramadol to be administered to the patient varies e.g. as a function of the patient""s weight, the indication and the degree of severity of the pain or disease. The amount of tramadol to be administered, and its release, are preferably adjusted so that it has to be taken at most twice a day and preferably only once a day.
If taken once a day, the forms of administration according to the invention preferably contain 10 to 1200 mg, particularly preferably 20 to 1000 mg and very particularly preferably 100 to 800 mg of tramadol.
If taken twice a day, the forms of administration according to the invention preferably contain 5 to 600 mg, particularly preferably 10 to 500 mg and very particularly preferably 50 to 400 mg of tramadol.
The forms of administration according to the invention can preferably be used for the control of pain or for the treatment of urinary incontinence, coughs, inflammatory reactions, allergic reactions, depression, drug abuse, alcohol abuse, gastritis, diarrhoea, cardiovascular disease, respiratory disease, mental illness or epilepsy, and particularly preferably for the control of pain or for the treatment of urinary incontinence or coughs.
The forms of administration according to the invention have the advantage that, immediately after preparation, their active substance release profile is stable on storage without the need for tempering, which normally follows drying, or for an expensive coating process. This makes it possible to reduce the production time and hence also the costs of producing the forms of administration according to the invention.
Furthermore, the release of the active substance tramadol from the forms of administration according to the invention, provided with a sustained-release coating applied from an aqueous medium, is surprisingly retarded far more than from the forms of administration, provided with a sustained-release coating of identical composition, which contain the active substance tramadol as tramadol hydrochloride. Application of the sustained-release coating film from an aqueous medium has the further advantage that the expensive recovery or organic solvents is not necessary and that the forms of administration according to the invention no longer contain solvent residues.
A further feature of the forms of administration according to the invention is that the release of the active substance tramadol therefrom is not affected by varying the release conditions within the conventional framework, e.g. by means of the ion concentrations of the buffers, the presence of surface-active substances or the application of different mechanical stresses.
The release profiles of the forms of administration according to the invention were determined as follows:
The form of administration according to the invention was tested in a cage apparatus or in a paddle stirrer, as described in the European Pharmacopoeia, at a release medium temperature of 37xc2x10.5xc2x0 C. and a speed of rotation of 100 rpm or 50 rpm in the case of the paddle stirrer, for 2 hours, in 600 ml of artificial gastric juice at pH 1.2. The form of administration was then tested for a further 8 hours in 900 ml of artificial intestinal juice at pH 7.2. The amount of tramadol saccharinate released at any given time was determined by HPLC. The values shown have been averaged over 3 samples in each case.
The invention is illustrated below with the aid of Examples 1 to 11. These illustrations are given solely by way of example and do not limit the general spirit of the invention.